Last night I checked the extruder settings and, sure enough, the target temp was set to 2 but the extruder temp showed as 1 even without any thermistor attached. I changed the setting for target temp to 0 and the whole machine started working just fine. It was very exciting to watch it go through the motions of printing a frame vertex. I took some video but I have not been able to get it to upload to Blogger. I am trying to reduce the size and convert it to other formats but no luck so far. I may try uploading it to YouTube first.
I managed to change my firmware settings last night so I now have all three axis moving correctly. I hit "home" and watched all three move at the same time. Very inspiring.
Then I decided that I would load up a Gcode file and get things moving, even though my extruder is still on the workbench. It was a good exercise since I hadn't even looked at the user manual for the host software. I managed to get the Gcode generated and loaded up but when I hit "print" it just sat there with the "estimated time to print" moving upward into the hundreds and then thousands of hours. I had to think about it for a while but I realized today that it was probably waiting for the extruder to reach operating temperature. I am going to try again this evening but first I will set the working temperature for the hot end to 0.
Here is a site that everyone should see. This guy has built his own 3d printer but it does not use the fused deposition technique of the Repraps. It harks back to the original 3d printers in that it uses a polymer resin that is hardened layer by layer using UV light. I don't know the details of his hardware but the resolution is really remarkable. The flute in these pictures is playable. He is trying to get plans or kits together (not too sure exactly where he is going yet) so this is definitely a site to put on your watch list.
One of the things that delayed my work on the Mendel over the last week or so was that my trusty HP TC1100 tablet computer was out of action. This was caused by my preparations to get another project underway after the Reprap is finished.
This is a small CNC router called the DIYLILCNC. It is open source and the plans are freely available on their website. It has a cutting area of 12"x14"x2". I am going to build one to complement the Reprap since it will be great for cutting small parts out of flat stock. The DIYLILCNC is constructed mostly out of stressed hardboard, called Masonite in some places. A full 4x8 sheet is required but it is very inexpensive and the parts are simply bolted together, much like a Mendel. All in all it is a very elegant little design and has the advantage of being complete, tested, and well documented. The parts are designed to be laser cut but, like Repraps, the user community has already begun their own redesigns. Someone has posted a set of cut patterns optimised for a CNC router. Since my daughter's school has a large CNC router setup I plan on doing some horse trading for the cutting service. Perhaps I can do a presentation on the Mendel for the shop students.
Instead of designing their own electronics hardware the lilcnc team simply used one of the commercial 3 axis kits that are now available from a number of sources. They also use an easily acquired Dremel tool as the cutter. I ordered my motors, electronics and power supply as a kit from China. I have no idea what the quality will be like but the price was worth taking a chance on (about $200 including shipping). The three NEMA 23 motors are slightly less powerful than the ones called for in the DIYLILCNC plans but they should do the job.
As far as my tablet being out of action - I tried to load an application called EMC2. It is an open source CNC control application and is the one most commonly used if you can't afford the (very expensive) commercial alternatives. Unfortunately, when I loaded it up it somehow corrupted my Nvidea drivers and I was unable to even boot the machine. It took the better part of a week to get things going again. Since I use that machine to run the Mendel it really slowed down the work on the current project. Perhaps I should stick to one project at a time. In any case, I discovered while troubleshooting the problem that the folks at the EMC2 website do not recommend running it on tablets or laptops since it is a realtime control program and the older laptop technology usually can't keep up with the cutter and will start dropping instructions. Oh well, Live and Learn.
I did a lot of work on small things this weekend. I finally greased the rails, adjusted the endstop tabs so they meet the endstops correctly, reloaded the firmware, and rewired the 12v system (it was very sloppy and would have caused problems eventually).
I now have all 3 axis moving smoothly. My only problem is that the X and Y axis move in reverse. They worked fine when I was jogging them but as soon as I tried to home them they shot to the wrong end of the rails. I don't have my control box wired up yet so I had no emergency stop button but I had my hand on the plug for the power brick so I was able to pull it and shut things down without any damage. I tried to reverse the direction of those two axis in the firmware but it had no effect. I suppose I have to dig deeper into the code. Either that or change the wiring of the motors themselves. Strangely, the Z axis moves correctly and I can home it without any problems.
I also worked quite a bit on my extruder. The hot end is assembled as well as most of the rest of the parts. I just need to epoxy the peek insulator into the main body of the extruder. My main problem now is that I still can't get the gears off of my used stepper motor. I am going to order a new one today and I will just have to wait for it to arrive.
I will start to assemble my control box this week. It will clean up my workbench a bit and I won't have to pull the plug anymore to shut the steppers off. It will only contain the power brick, a lighted on/off switch, for the 12v system, the emergency cuttoff, and the PID for my heated bed but keeping those things neat will be worth the effort.
Well, I just had a whole week off work but I am still not printing. Why, you ask? Because I am a lazy so-and-so. Also because there always seem to be a hundred things that need to be done before I can get to the Reprap work.
I have made some progress though. I have assembled both of my MakerGearHeatcores. They seem to be working perfectly. A small problem with them is that they did not come with the Molex connector that should be attached. I think that the later kits include it (it is shown in the assembly instructions on their website) but mine did not. Remember that I bought my kits last spring so they are from the early lots, things have been improved since then.
I also began assembling the geared extruder. I don't have bolts long enough for some of the assembly steps so I have been cutting lengths of threaded rod and placing a nylok nut on one end. It seems to work fine and it allows me to customize the lengths to whatever I need.
I also discovered another oversight on my part. When I ditched my plan to use a set of used stepper motors for the Mendel I purchased some new ones. Unfortunately they came in a set of three so I don't have one for the extruder. I will have to use one of the second hand motors for this but that means that I have to solve my problem with the gear that is stuck on the shaft. If I can't find a way to remove it without damaging the shaft or the motor I will have to buy another new one and wait for it to arrive. I guess that would not be too serious a problem since I am taking so long with these final steps but I will try to get the old gear off first.
More pictures and some video of the axis moving when I post next time.